When distracting thoughts arise (as they always do) during non-judgmental self-observation (aka "mindfulness") a useful tactic may be to put a label on them to help with letting go of them: "oops, now I'm worrying" ... "hmmm, that's just reminiscing again" ... "ooh, my foot is itching" ... and so forth. In the anthology Breath Sweeps Mind: A First Guide to Meditation Practice Joseph Goldstein calls it "mental noting" and observes:

You can also use the technique of mental noting to strengthen mindful awareness. The art of mental noting, as a tool of meditation, requires practice and experimentation. Labeling objects of experimentation as they arise supports mindfulness in many different ways.

Noting should be done very softly, like a whisper in the mind, but with enough precision and accuracy so that it connects directly with the object. For example, you might label each breath, silently saying in, out, or falling. In addition, you may also note every other appearance that arises in meditation. When thoughts arise, note thinking. If physical sensations become predominant, note pressure, vibration, tension, tingling, or whatever it might be. If sounds or images come into the foreground, note hearing or seeing.

The note itself can be seen as another appearance in the mind, even as it functions to keep us undistracted. Labeling, like putting a frame around a picture, helps you recognize the object more clearly and gives greater focus and precision to your observation.

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Be patient in learning to use this tool of practice. Sometimes people note too loudly, and it overshadows the experience. Sometimes people try too hard, becoming tight and tense with the effort. Let the note float down on the object, like a butterfly landing on a flower, or let it float up with the object, like a bubble rising. Be light, be soft, have fun.